Step 2: Insert into radio post

Conceived and photographed at red lights on the way to work. The knob was missing on my car radio when I inherited this car, and it is really annoying. When I scrapped an old CD player, its knob popped off while I was carting it around in the car. I got this idea when the knob rolled under my feet.

You will need:A radio missing a knobA knob from another useless device It is best if the knob has a slot in itA penny